Automated sugarcane harvesters are typically configured to sequentially sever standing canes from the ground, using one or more base cutters, and have processing apparatus including a conveyor or conveyors for carrying the cut canes rearward to a billet cutter for cutting into shorter billets. Sugarcane harvesters often also include apparatus for stripping or otherwise removing leaves from the cut canes, and one or more extractors for separating the leaves and other plant residue from the cut canes during the process. Typical extractors include a fan carried in a housing above one or more of the conveyors, configured to draw the leaves and other loose plant residue upwardly away from the heavier canes so that the canes continue on the conveyor or conveyors for additional processing or collection, and the leaves and other residue pass through the fan and are discharged with the fan exhaust, typically in a selectable direction by a directable fan hood or deflector disposed above the extractor fan housing. A disadvantage, however, is that the leaves and other residue pass through the fan which causes undesirable wear on the fan blades, and can occasionally wrap around the fan blades and/or possibly clog flow through the fan. Another disadvantage, for applications wherein it is desired for the leaves and other residue to remain largely intact, such as for collection for use as biomass or energy production, is that the fan will chop the leaves making them difficult or impossible to collect and use. It has also been observed that the residue that passes through the fan is more widely distributed over the field, which may not be desired if it is sought to collect it, e.g., for biomass. Reference in this regard, Wendte, et al., U.S. Pat. No. 6,272,819, which discloses and illustrates representative extractor apparatus of a sugarcane harvester.
As an alternative to passage through the extractor fan, it is contemplated according to the present invention to utilize a moving screen in front of the fan, to collect the residue flow toward the fan. A variety of moving screen apparatus have been developed in the past, but suffer from shortcomings. Reference in this regard, Ellis, U.S. Pat. No. 4,235,293 which discloses use of a moving scroll type screen for removing soil from a conveyed flow of potatoes. An observed limitation of this apparatus, however, is that the scroll encircles rollers above and below the entrance to the fan housing, and the scroll encircles the rollers so that the soil containing side of the scroll is facing the exposed fan, and soil deposits on the scroll not scraped off can be dislodged and drawn through the fan.
It is also known to locate rotary screens in the air intake path to heat exchangers, radiators, and the engine of work machines, including sugarcane harvesters. Reference in this regard, D'hondt U.S. Pat. No. 7,981,175. The D'hondt device provides a combination brush and blow-off capability for removing accumulated debris and residue from the rotary screen. However, a limitation is that it is used in association with a radially outwardly facing screen, and the blow-off apparatus covers a portion of the air flow path through the screen. This can be disadvantageous for high air flow applications such as the present extractor application wherein the screen is specifically intended to draw and collect a high volume of crop residue.
Accordingly, what is sought is a manner of adapting an extractor system of a harvester for reducing or eliminating passage of residue, namely, leaves, through the fan, to reduce wear and other attendant problems, and which overcomes one or more of the shortcomings and limitations set forth above.